MASP1 encodes a serine protease family with dual roles in complement activation and tissue pathology. The primary MASP-1 protein initiates the lectin pathway of complement activation 1, while its alternative splicing variant MASP-3 specifically catalyzes factor D (CFD) cleavage to activate the alternative complement pathway 123. This alternative pathway functions as an amplification loop enhancing overall complement-mediated immune responses 2. Beyond canonical complement roles, MASP1 contributes to pathological processes. Hepatocyte-derived MASP1-enriched extracellular vesicles activate hepatic stellate cells via p38 MAPK/ATF2 signaling to promote liver fibrosis 4, positioning MASP1 as a therapeutic target. MicroRNA-122-5p directly targets MASP1 to regulate coagulation and inflammation, with reduced MASP1 levels observed in sepsis-associated disseminated intravascular coagulopathy 5. Genetic variations in MASP1 associate with multiple diseases: 3MC syndrome mutations impair neural crest cell migration causing craniofacial abnormalities 6; MASP1 polymorphisms associate with fatigue severity in primary Sjögren's syndrome via effects on RTP4 expression and complement activation 7; and specific haplotypes increase susceptibility to chr3 Chagas disease cardiomyopathy 8. MASP1 SNPs significantly influence plasma concentrations of MASP-1, MASP-3, and MAp44 protein isoforms 9.